Method and device for monitoring a wear structure, in particular a sealing structure

ABSTRACT

A method for monitoring a wear structure including at least one wear element in a machine for generating or processing a fibrous material web, includes providing a time at which the wear element became operational, providing a time at which a defined first wear level of the wear element was reached, providing at least one further characteristic variable, and predicting a remaining operating time of the wear element from the knowledge of the times, in particular from a time difference between the times, as well as from the at least one further characteristic variable, by using a computer system. A device for carrying out the method is also provided.

The invention relates to a method for monitoring a wear structure, inparticular a sealing structure in a machine for producing or processinga fibrous web, according to the preamble of claim 1, and to a device formonitoring a sealing structure, according to the preamble of claim 13.

In machines for producing paper or board, a multiplicity of evacuatedrolls are used. In these suction rolls, it is usual for one or moresuction zones to be sealed off with respect to the inner wall of theroll shell, in order to prevent too high a drop in the vacuum andtherefore to reduce the suction action. In practice, this sealing isnormally carried out by means of so-called sealing strips, which arepressed with a certain pressure against the inner wall of the rollshell. These sealing strips are in frictional contact with the rollshell and, as a result, are subjected to comparatively high wear as aresult of abrasion.

To reduce the wear, it is known, for example from DE 10 2012 207 692, tointroduce a lubricant between roll shell and sealing strip. However,since the wear cannot be eliminated completely, the sealing strips haveto be replaced after a certain time. Because of the installationsituation of the sealing strips in the suction roll, the current stateof wear of the sealing strip can, however, generally not be determinedor determined only very roughly without opening the suction roll andtherefore interrupting the production process. Since, in the event oftoo late a replacement of the sealing strips, it is possible for damageto the suction roll to occur, the sealing strips are often replacedconsiderably before the end of their operating time, although this isassociated with increased costs. Therefore, from an economical point ofview, it is desirable to obtain more accurate information about thestate of wear of the sealing strip during continuous operation. From theprior art, for example DE 10 2012 208 811, it is known to integratesensors into the sealing strip which, during the operation of thesuction roll, supply information about the level of wear. In addition,in WO 03/056215, it is proposed to determine an estimate for theremaining operating time of the sealing strip from the knowledge of theinstallation time of the strip and of the current wear.

However, these systems have the deficiency that the wear of the sealingstrips is usually not carried out uniformly over time, and the estimateof the remaining operating time is only insignificantly more accuratethan the practical knowledge of the papermaker.

It is an object of the present invention to propose a method whichpermits a considerably more accurate prediction of the remainingoperating time of a wear element, in particular of a sealing strip, thanthe method known from the prior art.

The object is completely achieved by a method for monitoring a wearstructure as claimed in the characterizing part of claim 1, and by adevice for monitoring a sealing structure as claimed in thecharacterizing part of claim 13.

The method according to the invention describes a method for monitoringa wear structure in a machine for producing or processing a fibrous web.The wear structure comprises at least one wear element which, inparticular, is subjected to wear as a result of frictional contact.Furthermore, the sealing structure can also comprise still furthercomponents such as, for example, holders for the at least one wearelement or means for pressing the wear element onto a moving surface orelse means for moving the wear element.

A particularly preferred embodiment of this method according to theinvention is a method for monitoring a sealing structure for sealing atleast one negative or positive pressure zone adjoining a surface movingin a direction of movement in a machine for producing or processing afibrous web. The sealing structure comprises at least one sealingelement which is in frictional contact with the moving surface and as aresult is subjected to wear. The sealing structure can additionally alsocomprise still further components such as, for example, holders for theat least one sealing element or means for pressing the sealing elementonto the moving surface.

In a particularly preferred embodiment of the method, the moving surfaceis the rotating shell of a suction roll and the sealing element or thesealing elements is/are sealing strips which are pressed against theroll shell for the purpose of sealing. However, other sealing structuresare also conceivable, such as the sealing of a suction box on a movingfabric, for example.

In order to carry out the method according to the invention, a time z0at which the wear element or the sealing element was installed or becameoperational is provided. The provision of this or another time caneither be carried out automatically or else by means of a manual entry.Furthermore, a time z1 at which a defined first level of wear of thewear element or the sealing element was reached is provided. Thedifference between these two times describes the time which has elapseduntil the defined level of wear was reached. By means of anextrapolation, for example a linear extrapolation, a first estimate forthe remaining operating time of the wear element or the sealing elementcan already be obtained. For instance, it could be deduced: 50% wear inn days, this results in 100% wear in 2 times n days. However, ittranspires that the wear of the wear element or of the sealing elementdoes not necessarily proceed uniformly over time. For example, arelatively long stoppage of the machine or the intensified production ofgrades in which the machine can be operated only at low speed, etc., canlead to the remaining operating time of the sealing element beingconsiderably over-estimated or under-estimated. The invention thereforeprovides for at least one further characteristic variable K1 to beprovided which, for example, contains information about one or moreaspects which contribute to non-uniform wear of the wear element or ofthe sealing element. This can be data relating to the machine speed orstoppage times in the operating time period of the wear element or thesealing element. However, other data can also be relevant and providedas a further characteristic variable K1. By way of example but notconclusively, the following may be listed here: information about thelubricant monitoring, change in the internal roughness of the rollshell, number of roll revolutions, contact pressure of the sealingstrip, etc.

The prediction of a remaining operating time of the wear element or ofthe sealing element is carried out, according to the invention, by usingthe times z0 and z1 or the time difference between z0 and z1 and alsothe at least one further characteristic variable K1, by means of acomputer system. It is thus possible to calculate a considerablyimproved prediction of the remaining operating time of the wear elementor of the sealing element than is possible only on the basis of the timeinformation. By way of example, only the quite simple approach may bedescribed here in which, instead of the operating time z1-z0, aneffective operating time of the sealing element is used, that is to saythe time z1-z0 minus the stoppage times of the machine in this timeperiod. This effective operating time can then be extrapolated linearly,for example as described above. Alternatively, it is also possible todescribe the effective operating time via the number of roll revolutionsin the time period z1-z0. By extrapolation, it is then possible to makean estimate as to for how many roll revolutions the sealing element canstill be used. This can be converted on the basis of an average speed orelse the current speed into a remaining operating time. However, a largenumber of other methods for calculating the prediction of a remainingoperating time are also conceivable according to the invention.

After a prediction of the remaining operating time of the wear elementor of the sealing element has been carried out at the provision of thetime z1, this prediction can be monitored continuously and, for example,corrected on the basis of changes in the further characteristic variableK1 and, of course, with incorporation of the current date or the currenttime.

Further advantageous embodiments of the invention are described in thefurther subclaims.

Thus, in preferred embodiments of the invention, it may be advantageousthat, in addition to the characteristic variable K1, additional, furthercharacteristic variables K2, K3, K4 . . . are also provided and thesecharacteristic variables are also incorporated into the prediction ofthe remaining operating time of the wear element or of the sealingelement. With the aid of these additional further characteristicvariables, the quality of the prediction can be improved further in manycases. Depending on the application, up to four characteristic variablesor up to eight such characteristic variables or even more than eightsuch further characteristic variables can also be incorporated into theprediction of the remaining operating time.

In advantageous embodiments of the invention, the characteristicvariable K1 and/or one or more of the additional further characteristicvariables K2, K3, K4 . . . can describe one or more aspects of theoperating mode of the machine. In particular, the operating mode of themachine since the time at which the sealing element became operationalcan be described by these characteristic variables. However, provisioncan also be made for the characteristic variables also to includeinformation from the time before the installation of the wear element orof the sealing element. In particularly advantageous embodiments,information about future operating modes of the machine can also beprovided as a further characteristic variable. Here, this can be, forexample, data from production planning such as, for example, a usualgrade running order, or information about planned stoppages, etc.

Provision can be made, for example, for the further characteristicvariable K1 and/or one or more of the additional further characteristicvariables K2, K3, K4 . . . to describe the machine speed, the operatingtimes of the machine, the stoppage times of the machine, the type and/orquantity of the products produced, the contact pressure of the sealingelement onto the moving surface. However, other or further variables arealso possible.

Here, it should be mentioned that this data which is used for thecharacteristic variables K1, K2, K3, K4 . . . originates from varioussources and that the characteristic variables can be described by meansof various measured values. Thus, the machine speed can be presentdirectly as a production speed of the machine in m/min. However, it canalso be described, for example, in the form of the rotational speed of asuction roll, the rotational speed of one or more drives present or thelike. In addition, the number of roll revolutions starting from aspecific time can be used as a description of the machine speed. Thesedata items all describe the production speed of the machine and can beconverted into one another very simply, if appropriate given theknowledge of geometric variables such as a roll circumference or thelike. It is clear to those skilled in the art that these differentdescriptions of the same property are identical for their use ascharacteristic variable K1, K2, K3, K4 . . . . The same is true for analternative description of the data which describes the stoppage timesof the machine, the type and/or quantity of the products produced, thecontact pressure of the sealing element onto the moving surface, etc.

By means of the combinations of a plurality of characteristic variables,a multiplicity of advantageous data items can be used to determine theremaining operating time of the sealing element. Some will be listed byway of example here.

Thus, in one advantageous embodiment, provision can be made, forexample, for the characteristic variable K1 to be a variable whichdescribes the machine speed, and for the characteristic variable K2 todescribe the type and/or quantity of the products produced or thecontact pressure of the sealing element onto the moving surface.

In a further advantageous embodiment, provision can be made, forexample, for the characteristic variable K1 to indicate the number ofroll revolutions since a specific time (e.g. the installation of thesealing element)—a type of description of the machine speed—and for thecharacteristic variable K2 to describe the internal roughness of theroll shell.

A characteristic variable K3 which contains information about thelubricant supply of the sealing element (e.g. the quantity oflubricating water) can in both cases be used additionally or else as areplacement for one of the characteristic variables K1 or K2.

The combinations of characteristic variables indicated here do not formany final enumeration of the possible combinations according to theinvention but are intended merely to document by way of example thepossibilities of the configuration of the method according to theinvention.

The provision of the data can be carried out in an extremely wide rangeof ways, according to the invention. For example, provision can thus bemade for the further characteristic variables to be retrievedcontinuously and stored in a database. This database can be created, forexample, on the computer of the computer system on which the calculationis carried out or else on another computer. Provision can also be madefor this other computer to be operated not by the operator of the papermachine but by another operator, and for the data to be transmitted tothis database.

In a further advantageous embodiment of the invention, after the timez1, at least one further time z2, preferably a plurality of furthertimes z3, z4 . . . can be provided, at which a defined second, third,fourth . . . level of wear has been reached, wherein in each case when anew time is provided the remaining operating time can be re-determinedby incorporating all the times already provided and the furthercharacteristic variable or the further characteristic variables. Theprovision of further times at which a defined level of wear has beenreached is therefore advantageous since the accuracy of the predictionof the remaining operating time is therefore improved further.Particularly toward the end of the service life of the sealing element,this is advantageous in order to be able to choose the most optimal timepossible for the replacement of the sealing element.

It is particularly advantageous if the provision of at least one of thetimes z1, z2, z3, z4 . . . , preferably all the times which areincorporated into the prediction of the remaining operating time, iscarried out by means of a signal which is transmitted directly orindirectly from a sensor in the wear element or the sealing element tothe computer system. Here, for economic reasons, it is usual for amaximum of two or three sensors to be used in a sealing element.However, more than three sensors in a sealing element are also possible.

Furthermore, provision can advantageously be made for at least one ofthe further characteristic variables K1, K2, K3, K4 . . . , preferably aplurality of the further characteristic variables K1, K2, K3, K4 . . . ,to be provided by a control system, which is also used for themonitoring, open-loop control and/or closed-loop control of the machine.

For the method, it may be advantageous if one of the levels of wear isdefined between 80% and 50% remaining wear. The exact knowledge that acomparatively early level of wear has been reached makes it possible todetermine a first prediction of the remaining operating time of the wearelement or of the sealing element very early.

Likewise, it may be advantageous for the method if one of the levels ofwear is defined between 20% and 10% remaining wear, preferably between20% and 15% remaining wear. The exact knowledge that a comparativelylate level of wear has been reached permits a more accurate predictionof the remaining operating time of the wear element or of the sealingelement.

Furthermore, it may be advantageous that the remaining operating time isdisplayed on a display device.

In a further variant according to the invention, the method canadditionally comprise the steps:

d) defining at least one threshold value for the remaining operatingtime

e) checking whether the remaining operating time falls below the atleast one defined threshold value

f) generating an advice signal if the remaining operating time fallsbelow the at least one defined threshold value.

Such a threshold value can, for example, be chosen such that a routinestoppage of the machine, during which the sealing element can bechanged, always falls in the remaining operating time. The thresholdvalue can also be chosen such that sufficient time still remains for theoperator to re-order a new wear element or sealing element. There isalso the possibility of defining a plurality of threshold values, atwhich signals for different actions are generated (e.g. a signal forinitiating an order and a later signal for the planning of thereplacement of the sealing element).

The advice signal generated or one of the advice signals generated canbe displayed, for example, on an optical or acoustic display deviceand/or forwarded to a further computer system. Here, according to theinvention, provision can be made, for example, for such a signal to beforwarded to an electronic procurement system.

In advantageous embodiments of the method, the prediction of a remainingoperating time of the wear element or of the sealing element can becarried out in the form of a single value or else in the form of aninterval. A combination of the two is also possible. Thus, for example,provision can be made that, in addition to the estimated remainingoperating time, a lower limit and an upper limit for the remainingoperating time are also indicated. These can be determined, for example,under the assumption that one or more of the further characteristicvariables K1, K2, K3, K4 . . . will change in the future by a certainpercentage. By way of example, the possibility should be mentioned herethat the lower limit indicates how long the remaining operating time isif in the future the average machine speed is increased by 5% or 10% orthe average stoppage time of the machine is reduced by 5% or 10%. In asimilar way, the remaining operating time would be specified as an upperlimit for the case in which in the future the average machine speed isreduced by 5% or 10% or the average stoppage time of the machine isincreased by 5% or 10%.

In this way, the operator is given advice about the reliability of theestimate and also advice as to the extent to which he can act on theremaining operating time by using changes in the operating mode of theplant. For example, this may be helpful in the question as to whetherthe sealing element can then also remain installed until the nextplanned stoppage if production is carried out with a somewhat increasedspeed.

Furthermore, the invention comprises a device for monitoring a sealingstructure for sealing at least one negative or positive pressure zoneadjoining a surface moving in a direction of movement in a machine forproducing or processing a fibrous web. The device comprises at least onesealing element having at least one wear sensor, preferably a pluralityof wear sensors, a computer system and means for signal transmissionfrom the at least one wear sensor to the computer system. The inventionprovides for a prediction of the remaining operating time of the sealingelement to be carried out with the aid of the computer system by meansof a method as claimed in one of claims 1-12.

In an advantageous embodiment of the device, the at least one sealingelement can comprise or consist of a sealing strip.

According to an advantageous embodiment, the sealing element, inparticular also the sealing strip, comprises at least one wear sensorwhich indicates a level of wear between 80% and 50% remaining wearand/or a wear sensor which indicates a level of wear between 20% and 10%remaining wear.

According to a further advantageous embodiment, the device comprises adisplay device which displays the remaining operating time of thesealing element. Provision can also be made for the device not tocomprise a dedicated display device but to share a display device withother devices. Thus, the display device can be, for example, a monitorin a control room of the machine, on which still other values aredisplayed beside the remaining operating time or else alternatingtherewith.

In a preferred embodiment, provision can be made for the at least onewear sensor to comprise at least one hose which is filled with a mediumand is destroyed with progressive wear of the sealing element. Thepressure drop produced as a result can be determined and—depending onthe installation position of the hose—can be used as an indication thata certain level of wear has been reached.

In a further preferred embodiment, provision can be made for the atleast one wear sensor to comprise at least one optical fiber or anelectrical conductor, which is destroyed with progressive wear of thesealing element.

Here, a change in the electrical resistance or an interruption to thecurrent flow or a reduction or interruption in the conduction of lightcan be established and can serve as an indication that—depending on theinstallation position of the conductor—a certain level of wear has beenreached.

In a further advantageous embodiment of the invention, provision can bemade for the at least one wear sensor to comprise or consist of atemperature sensor. Such a temperature sensor can fulfill a dualfunction. Firstly, it supplies data about the temperature of the sealingelement, that is to say, for example, the sealing strip, at theinstallation position of the temperature sensor. With progressive wearof the sealing element, the temperature sensor can then be damaged ordestroyed. Thus, for example, the absence of a temperature measuredsignal from the temperature sensor can provide an indication that thewear of the sealing element has progressed as far as the installationposition of the temperature sensor. Frequently, by means of such atemperature sensor, a rise in the temperature can be measured evenbefore the destruction of the sensor by wear. In addition, informationabout the state of wear of the sealing element can be obtained from theknowledge of this temperature rise.

A further wear structure which can be monitored by means of a methodaccording to the invention is a screen for treating a fibroussuspension. The screen baskets used there are wear elements which haveto be replaced after some time. The accurate state of wear of the screenbasket cannot be detected from outside. In particular, the most accurateprediction possible of the remaining operating time of the screen basketis very desirable.

A device which can be used for the use of the method according to theinvention is described below in a further inventive idea.

This relates to a system for monitoring the state of a screen basket ofa screen for treating a fibrous suspension.

The aim during screening is the separation of disruptive solidconstituents from fibrous suspensions. Separation is carried out byscreening in accordance with the particle features size, shape anddeformability. Screening is an important separation method in thepreparation of paper for recycling. Depending on the level of pulpingand the loading of the suspension with foreign materials and fiberspecks, different screens are used. Amongst others, so-called basketscreens with a screen basket arranged in a housing are used.

In the previously known basket screens, the technical data of the screenbasket is stamped onto an end ring of the screen basket. Since thescreen basket is arranged in the housing of the relevant screen, readingthis technical data is relatively complicated. In addition, the state ofwear of the screen basket remains unknown, particularly also since noservice life or history for the screen baskets is present and nooperating data is available either.

The further inventive idea is based on the object of specifying a systemfor monitoring the state of a screen basket of a screen for treating afibrous suspension in which the aforementioned problems are eliminated.The intention is in particular to ensure faster fault-free reading ofthe technical data relating to the screen basket and to permit morecomprehensive monitoring of the state of the screen basket from outside.

The object of the further inventive idea is achieved by a system havingthe features of clause 1. Preferred embodiments of the system accordingto the invention can be gathered from the further clauses, the presentdescription and the drawing.

According to the further inventive idea, the system for monitoring thestate of a screen basket of a screen for treating a fibrous suspensioncomprises a cable-free identification unit assigned to the screen basketarranged in a housing of the screen and an external, in particularmobile, reading unit for the non-contact reading of technical datarelating to the screen basket from the identification unit and forproducing a connection to a further external database containing datarelating to the screen.

On the basis of this configuration, the technical data relating to thescreen basket can be read quickly and reliably in a cable-free andnon-contacting manner from outside, i.e. from outside the housing of thescreen. In addition, via the external reading unit, further datarelating to the screen contained in an external database can beaccessed, which means that more comprehensive monitoring of the state ofthe screen basket is made possible. Here, as the screen basket isinstalled, a corresponding item of screen basket information can be readinto the external database. When the technical data relating to thescreen basket is subsequently read from the identification unit assignedto the screen basket, the necessary allocation of data contained in thedatabase to this screen basket can then be produced. The further datarelating to the screen can, for example, be collected via a controlsystem of the factory in which the screen is installed and supplied tothe external database. Sales staff and customers can each be issued withan in particular mobile reading unit, so that these can monitor thescreen basket from outside, i.e. from outside the housing.

A respective reading unit preferably comprises a display for reproducingfurther data relating to the screen and retrieved from the externaldatabase.

According to an expedient practical embodiment of the system, theidentification unit comprises at least one RFID chip(RFID=radio-frequency identification).

Such an RFID chip in particular constitutes a transponder which containsthe technical data relating to the screen basket. The transponder is aradio communication means which picks up and automatically answersincoming signals. The coupling can be made by alternating magneticfields of low range, generated by the reading unit, or by high-frequencyradio waves. It is therefore possible not only to transmit data but alsoto supply the transponder with energy. For greater ranges, an activeRFID chip with its own power supply, for example, is also conceivable.

The reading device can contain software which controls the actualreading process for reading the technical data relating to the screenbasket from the identification unit or the RFID chip. In addition, thereading unit can comprise RFID middleware with an interface to theexternal database.

The identification unit preferably comprises at least one RFID chipassigned to the screen basket of the screen.

According to an expedient practical embodiment of the system accordingto the further inventive idea, the identification unit comprises both anRFID chip assigned to the screen basket of the screen and also an RFIDchip assigned to the housing of the screen, wherein the RFID chipassigned to the screen basket can be coupled via a software coupling tothe RFID chip assigned to the housing, and the RFID chip assigned to thehousing can be read via the reading unit.

Therefore, the reading unit can produce a connection between the RFIDchip assigned to the housing and the external database. In this case,the connection between the RFID chip and the external database is notimpaired by the generally metallic housing of the screen.

According to an alternative embodiment of the system, however, the RFIDchip assigned to the screen basket of the screen can also be readabledirectly via the reading unit.

In particular in the case in which the RFID chip assigned to the screenbasket of the screen can be read directly via the reading unit, the RFIDchip assigned to the screen basket of the screen is preferably arrangedin the region of the opening of the screen that can be closed via acover. In order to read the relevant RFID chip, the cover of the screencan then be taken off, whereupon the RFID chip assigned to the screenbasket of the screen can be read directly by means of the reading unit.

The RFID chip assigned to the screen basket of the screen can inparticular be arranged on or in an end ring of the screen basket.

In particular for the aforementioned reasons, it is advantageous if theRFID chip assigned to the screen basket of the screen is arranged on orin an end ring of the screen basket that is adjacent to the opening ofthe screen that can be closed by a cover.

Here, the RFID chip assigned to the screen basket of the screen ispreferably arranged on the upper side of the end ring, facing theopening of the screen.

It is also advantageous in particular if the RFID chip assigned to thescreen basket of the screen is arranged on the radial inner side of theend ring, by which means the accessibility of the RFID chip for couplingto the reading unit is further improved.

Also conceivable, for example, is an embodiment in which the RFID chipassigned to the screen basket of the screen is accommodated so as to becountersunk in the end ring. The RFID chip accommodated so as to becountersunk in the end ring of the screen basket is preferablyencapsulated here in plastic or preferably Teflon. Such a covering isexpedient since the screen basket is generally reconditioned, i.e. inparticular chromium-plated and electro-polished.

The aforementioned arrangement of the RFID chip assigned to the screenbasket of the screen on or in an end ring of the screen basket takesaccount, amongst other things, of the fact that the end rings of arod-type screen basket with rods extending between these end rings aresubject to lower wear than the rods.

The further data relating to the screen is preferably stored togetherwith the technical data relating to the screen basket in the externaldatabase. Via the technical data read from the identification unitassigned to the screen basket, the assignment to the further datarelating to the screen can thus be made in the external database.

According to a preferred practical embodiment of the system according tothe further inventive idea, the further data relating to the screen thatcan be retrieved from the external database via the reading unitcomprises production data of the screen basket, service life data of thescreen basket, operating data of the screen, wear data of the screenbasket and/or the like.

Here, the production data of the screen basket can include, for example,the design, the material, the size and so on of the screen basket. Theservice life data of the screen basket can, for example, include datarelating to the reconditioning of the screen basket, relating to storagetimes and so on. The operating data of the screen comprise, for example,the running time, the flow/pressure at the end ring/outlet of thescreen, the rotational speed and so on. This information can beobtained, for example, via the machine control system of the screen.

It is also advantageous in particular if the system according to theinvention comprises data-processing means in order, on the basis of theservice life of previous screen baskets, the entire throughputpreviously treated by the screen basket, the rotational speed of thescreen basket, the energy balance between the end ring and the outletsof the screen and/or the like, to determine the level of wear of thescreen basket and therefore the next change date for the screen basket.In particular, provision can advantageously be made for a prediction ofthe remaining operating time of the screen basket to be determined bymeans of the method according to the invention on the basis of thisdata.

A system for monitoring the state of a screen basket of a screenaccording to the further inventive idea can be used in a plant forproducing a fibrous web, either on its own or in combination with adevice according to the invention for monitoring a sealing structure.Such a combination offers the advantage, amongst other things, that as aresult the operator obtains more comprehensive knowledge relating to thecurrent state of important wearing parts in his plant. Thus, forexample, optimized stoppage planning can be carried out. A planned plantstoppage can then be scheduled, for example, such that sealing stripsand screen baskets can be replaced jointly.

In the following text, essential features of the further inventive ideawill be described once more in compact form by using numbered clausesreferring back to one another. The designations placed in brackets referto FIGS. 3 and 4.

The further inventive idea is subsequently also explained in more detailon the basis of an exemplary embodiment with reference to the drawings.

CLAUSES

-   -   Clause 1. A system (10) for monitoring the state of a screen        basket (12) of a screen for treating a fibrous suspension,        comprising a cable-free identification unit (14) assigned to the        screen basket arranged in a housing of the screen, and an        external, in particular mobile, reading unit (16) for the        non-contact reading of technical data (18) relating to the        screen basket (12) from the identification unit (14) and for        producing a connection to a further external database (20)        containing data relating to the screen.    -   Clause 2. The system as claimed in clause 1, characterized in        that the reading unit (16) comprises a display for reproducing        further data relating to the screen and retrieved from the        external database.    -   Clause 3. The system as claimed in clause 1 or 2, characterized        in that the identification unit (14) comprises at least one RFID        chip.    -   Clause 4. The system as claimed in clause 3, characterized in        that the identification unit (14) comprises at least one RFID        chip assigned to the screen basket (12) of the screen.    -   Clause 5. The system as claimed in clause 4, characterized in        that the identification unit (14) comprises both an RFID chip        assigned to the screen basket (12) of the screen and also an        RFID chip assigned to the housing (24) of the screen, wherein        the RFID chip assigned to the screen basket (12) can be coupled        via a software coupling to the RFID chip assigned to the housing        (24), and the RFID chip assigned to the housing can be read via        the reading unit (16).    -   Clause 6. The system as claimed in clause 4, characterized in        that the RFID chip assigned to the screen basket (12) of the        screen can be read directly via the reading unit (16).    -   Clause 7. The system as claimed in at least one of the preceding        clauses, characterized in that the RFID chip assigned to the        screen basket (12) of the screen is arranged in the region of        the opening of the screen that can be closed via a cover.    -   Clause 8. The system as claimed in at least one of the preceding        clauses, characterized in that the RFID chip assigned to the        screen basket (12) of the screen is arranged on or in an end        ring (22) of the screen basket (12).    -   Clause 9. The system as claimed in at least one of the preceding        clauses, characterized in that the RFID chip assigned to the        screen basket (12) of the screen is arranged on or in an end        ring (22) of the screen basket (12) that is adjacent to the        opening of the screen that can be closed by a cover.    -   Clause 10. The system as claimed in clause 9, characterized in        that the RFID chip assigned to the screen basket (12) of the        screen is arranged on the upper side of the end ring (22) that        faces the opening of the screen.    -   Clause 11. The system as claimed in clause 9, characterized in        that the RFID chip assigned to the screen basket (12) of the        screen is arranged on the radial inner side of the end ring        (22).    -   Clause 12. The system as claimed in clause 9, characterized in        that the RFID chip assigned to the screen basket (12) of the        screen is accommodated so as to be countersunk in the end ring        (22).    -   Clause 13. The system as claimed in clause 12, characterized in        that the RFID chip accommodated so as to be countersunk in the        end ring of the screen basket (12) is provided with a covering        or encapsulation in particular consisting of plastic and        preferably of Teflon.    -   Clause 14. The system as claimed in at least one of the        preceding clauses, characterized in that the further data        relating to the screen is stored together with the technical        data (18) characterizing the screen basket (12) in the external        database (20).    -   Clause 15. The system as claimed in at least one of the        preceding clauses, characterized in that the further data        relating to the screen that can be retrieved from the external        database (20) via the reading unit (16) comprises production        data of the screen basket (12), service life data of the screen        basket (12), operating data of the screen and/or the like.    -   Clause 16. The system as claimed in at least one of the        preceding clauses, characterized in that it comprises        data-processing means in order, on the basis of the service life        of previous screen baskets, the entire throughput previously        treated by the screen basket (12), the rotational speed of the        screen basket (12), the energy balance between the end ring and        the outlets of the screen and/or the like, to determine the        level of wear of the screen basket (12) and therefore the next        change date for the screen basket (12).

Although the method according to the invention can be used particularlyadvantageously in the cases outlined above, that is to say formonitoring a sealing structure and/or for monitoring a screen, it is notrestricted to these applications.

The invention will be explained further below by using schematicfigures, not to scale.

FIG. 1 shows, schematically, the essential components of the methodaccording to the invention.

FIG. 2 shows, schematically, a detail from a sealing strip in a deviceaccording to the invention.

FIGS. 3 and 4 show, in a purely schematic illustration, an exemplaryembodiment of a system for monitoring the state of a screen basketaccording to the further inventive idea.

FIG. 1 shows, schematically, a sealing strip 1 which is in frictionalcontact with a moving surface 200. This sealing strip 1 can be used in asuction roll to seal off a suction or blowing zone with respect to thesurroundings. However, it can also be in contact with a fabric, inparticular a wire or a press felt, in order for example to seal off asuction box. The sealing strip 1 in FIG. 1 comprises a wear sensor 2.This sensor 2 generates a signal as soon as a defined level of wear ofthe sealing strip 1 is reached. FIG. 1 shows a sealing strip 1comprising a sensor 2, but sealing strips 1 frequently comprise multiplewear sensors, preferably two or three. As a result, it is possible todefine multiple levels of wear at which, when they are reached, thesealing strip 1 transmits a signal. Advantageously, one of the levels ofwear can be defined between 80% and 50% remaining wear. The exactknowledge of reaching a comparatively early level of wear makes itpossible to determine a first prediction of the remaining operating timeof the sealing element 1 very early.

Likewise, it may be advantageous if one of the levels of wear is definedbetween 20% and 10% remaining wear, preferably between 20% and 15%remaining wear. The exact knowledge of reaching a comparatively latelevel of wear permits a more accurate prediction of the remainingoperating time of the sealing element 1. However, the sensors 2 can alsobe positioned such that they provide a signal at levels of wear otherthan those specified above, in particular also between 50% and 20%remaining wear. However, it is important for the method to know at whatlevel of wear the respective sensor 2 transmits a signal. This isdefined before the installation and the sensors are positionedappropriately.

The sensor signal is transmitted to a computer system via a signal line5. The transmission can be carried out in a cable-bound or cable-freemanner, for example via WLAN, Bluetooth or similar suitable signal lines5. In the example shown in FIG. 1, one or more further characteristicvariables are additionally transferred to the computer system 3. Thesecharacteristic variables are transmitted here by the control system 6 ofthe machine and can describe operating states of the machine, such as,for example, machine speeds, operating times of the machine, thestoppage times of the machine, the type and/or quantity of the productsproduced, or the contact pressure of the sealing element onto the movingsurface. These characteristic variables can be transmitted to thecomputer system 3 continuously or at specific discrete times.

On the basis of the time z0 at which the sealing strip 1 was installedand the time z1 at which a specific level of wear was reached, togetherwith the further characteristic variables from the control system 6, thecomputer system 3 calculates a prediction for the remaining operatingtime of the sealing strip 1. The time z1 is transmitted here by means ofa signal from the sensor 2 in the sealing strip 1. If more than onesensor 2 is installed, if appropriate signals are transmitted to thecomputer system 3 at further times z2, z3, z4 . . . , by which means theprediction can be improved by renewed calculation.

The sensors usually supply a signal to the computer system 3 only at thediscrete times z1, z2, z3, z4 . . . . At the times in between, thecomputer system updates the remaining running time continuously by usingthe characteristic variables from the control system and the currenttime.

The computer system 3 usually has a display device 4, on which theremaining operating time can be displayed.

FIG. 1 shows the computer system 3 and the control system 6 asphysically separated objects which are connected to each other by meansof a cable-bound or cable-less signal line 5 a. However, it is alsopossible for the two computer systems to be implemented in one unit. Inthis case, the calculation of the prediction of the remaining operatingtime can be carried out on a computing unit of the control system 6. Theremaining operating time can then be displayed, for example, on one ormore monitors in a control room of the machine.

In the system shown in FIG. 1, the computer system 3 is additionallyconnected to a further computer system 7 via a signal line 5 b. This canbe an electronic procurement system 7. Once the remaining operating timeof the sealing strip 1 reaches a previously defined threshold value, asignal can then be transmitted to the procurement system 7 in order totrigger a timely purchase of a new sealing strip 1 or the like.Alternatively or additionally, when another or the same threshold valueis reached, a signal can also be transmitted to a further computersystem 7 which plans or administers the planning of maintenance work onthe machine.

FIG. 2 shows a detail of a sealing strip 1 for a device according to theinvention. The sealing strip 1 has a certain maximum wear volume 30 inthe direction of wear V. Once this volume 30 has been removed by thefrictional contact of the sealing strip 1 with the moving surface 200 orby other effects, the sealing strip 1 can no longer fulfill its functionand it is even possible for damage to occur to the moving surface 200,for example the suction roll shell or the fabric. The remainingoperating time of the sealing strip 1 is therefore the time intervaluntil the maximum wear volume has been removed completely over thelength L of the sealing strip 1, at least at one location. In thesealing strip shown in FIG. 2, three wear sensors 2 a, 2 b, 2 c areprovided. They can each be implemented as a hose which is filled with amedium, for example air or water. However, other types of wear sensors 2a, 2 b, 2 c are also imaginable, such as, for example, optical sensors(optical fibers) or electrical conductors. The first sensor 2 a can bepositioned, for example, such that it outputs a signal as soon as only alevel of wear between 80% and 50% of the maximum wear volume 30 is stillavailable. The third sensor 2 c can be positioned, for example, suchthat it outputs a signal as soon as only a level of wear between 20% and10% of the maximum wear volume 30 is still available. The second sensor2 b can be positioned between the two others and, for example, output asignal as soon as only a level of wear between 40% and 30% of themaximum wear volume 30 is still available. These values are to beunderstood as exemplary and can also be considerably different,depending on situation and installation position.

It is advantageous that the last sensor 2 c is positioned such that, atthe time of the sensor signal or reaching the appropriate level of wear,sufficient operating time of the sealing element 1 still remains thatsufficient time is left for planned and controlled maintenance orreplacement of the sealing element—preferably within the context of aroutine stoppage of the machine.

In the drawing, FIG. 3 shows, in a purely schematic illustration, anexemplary embodiment of a system 10 for monitoring the state of a screenbasket 12 of a screen for treating a fibrous suspension according to thefurther inventive idea.

According to FIG. 4, the system 10 comprises a cable-free identificationunit 14 assigned to the screen basket 12 arranged in a housing 24 of thescreen, and an external, in particular mobile, reading unit 16 for thenon-contact reading of technical data 18 relating to the screen basket12 from the identification unit 14 and for producing a connection to anexternal database 20 containing further data relating to the screen.

The reading unit 16 can comprise a display for reproducing further datarelating to the screen and retrieved from the external database.

The identification unit 14 can comprise at least one RFID chip. In thiscase, it comprises at least one RFID chip assigned to the screen basket12 of the screen.

According to an exemplary embodiment of the system according to thefurther inventive idea, the identification unit 14 can comprise both anRFID chip assigned to the screen basket 12 of the screen and an RFIDchip assigned to the housing 24 of the screen, wherein the RFID chipassigned to the screen basket 12 can be coupled via software coupling tothe RFID chip assigned to the housing 24, and the RFID chip assigned tothe housing 24 can be read via the reading unit 16.

According to an alternative exemplary embodiment of the system 10, theRFID chip assigned to the screen basket 12 of the screen can also bereadable directly via the reading unit 16.

In particular in the case in which the RFID chip assigned to the screenbasket 12 of the screen is readable directly via the reading unit 16,the RFID chip assigned to the screen basket 12 of the screen isexpediently arranged in the region of the opening of the screen that canbe closed via a cover.

The RFID chip assigned to the screen basket 12 of the screen can inparticular be arranged on or in an end ring 22 of the screen basket 12that is adjacent to the opening of the screen that can be closed by acover. In the present case, the RFID chip assigned to the screen basket12 of the screen is accordingly arranged on or in the upper end ring 22of the screen basket 12.

The RFID chip assigned to the screen basket 12 of the screen can bearranged, for example, on the upper side of the end ring 22, facing theopening of the screen, or else on the radial inner side of the end ring22.

However, also conceivable, for example, is an embodiment in which theRFID chip assigned to the screen basket 12 of the screen is accommodatedso as to be countersunk in the end ring 22. The RFID chip accommodatedso as to be countersunk in the end ring 22 of the screen basket 12 canbe provided with a covering consisting in particular of plastic andpreferably of Teflon. By using such a covering, account is taken of thefact that the screen basket 12 is generally reconditioned, i.e.chromium-plated and electro-polished.

The further data relating to the screen can be stored together with thetechnical data relating to the screen basket 12 in the external database20. Via the technical data 18 read from the identification unit 14 of arespective screen basket 12, the relevant further data contained in theexternal database 20 can thus be assigned to the screen basket 12.

The further data relating to the screen that can be retrieved from theexternal database 20 via the reading unit 16 can in particular compriseproduction data of the screen basket 12, service life data of the screenbasket 12, operating data of the screen and/or the like. The productiondata of the screen basket 12 comprises, for example, data relating tothe design, the material, the size or the like of the screen basket 12.The service life data of the screen basket 12 can comprise, for example,data relating to the reconditioning of the screen basket 12, storagetimes and so on. The operating data of the screen comprises, forexample, data relating to the running time, the flow/pressure at the endring/outlet of the screen, data relating to the rotational speed of thescreen basket 12 and/or the like. The relevant information can inparticular be supplied by the machine control system of the screen.

Such a system can also be monitored by means of the method according tothe invention. As a result, a prediction of the remaining operating timeof the wear element 12, that is to say of the screen basket 12, issupplied. This information can be used, for example, for optimizing thestoppage planning.

In addition, the system 10 according to the further inventive idea, forexample, can comprise data-processing means integrated in the readingdevice 16 and/or in the external database 20, in order, on the basis ofthe service life of previous screen baskets, the entire throughputpreviously treated by the screen basket 12, the rotational speed of thescreen basket 12, the energy balance between the end ring and theoutlets of the screen and/or the like, to determine the level of wear ofthe screen basket 12 and therefore the next change date for the screenbasket 12.

1-14. (canceled).
 15. A method for monitoring a sealing structure forsealing at least one negative or positive pressure zone adjoining asurface moving in a direction of movement in a machine for producing orprocessing a fibrous web, the method comprising the following steps:providing a sealing structure including at least one sealing elementbeing in frictional contact with the moving surface and thus beingsubjected to wear; providing a time z0 at which the sealing elementbecame operational; providing a time z1 at which a defined first levelof wear of the sealing element was reached; providing at least onefurther characteristic variable describing a machine speed, operatingtimes of the machine, stoppage times of the machine, at least one oftype or quantity of products being produced, or a contact pressure ofthe sealing element onto the moving surface; and using a computer systemfor predicting a remaining operating time of the sealing element fromthe times z0 and z1 and the at least one further characteristicvariable.
 16. The method according to claim 15, which further comprisesusing the computer system to predict the remaining operating time of thesealing element from a time difference between z0 and z1 and the atleast one further characteristic variable.
 17. The method according toclaim 15, which further comprises providing additional furthercharacteristic variables in addition to the characteristic variable, andincorporating the further characteristic variables into the step ofpredicting the remaining operating time.
 18. The method according toclaim 17, which further comprises using at least one of the furthercharacteristic variable K1 or one or more of the additional furthercharacteristic variables to describe one or more aspects of an operatingmode of the machine.
 19. The method according to claim 18, which furthercomprises selecting the operating mode of the machine as a time at whichthe sealing element became operational.
 20. The method according toclaim 17, which further comprises using one or more of the additionalfurther characteristic variables to describe the machine speed, theoperating times of the machine, the stoppage times of the machine, atleast one of the type or quantity of the products being produced, or thecontact pressure of the sealing element onto the moving surface.
 21. Themethod according to claim 17, which further comprises: providing atleast one or a plurality of further times occurring after the time z1and defining further levels of wear having been reached; andre-determining the remaining operating time whenever a new time isprovided by incorporating all of the times already provided and thefurther characteristic variable or the additional further characteristicvariables.
 22. The method according to claim 17, which further comprisescarrying out the step of providing at least one or all of the timesincorporated into the prediction of the remaining operating time byusing a signal transmitted directly or indirectly from a sensor in thesealing element to the computer system.
 23. The method according toclaim 17, which further comprises using a control system to provide atleast one or all of the further characteristic variables and to monitorat least one of open-loop control or closed-loop control of the machine.24. The method according to claim 21, which further comprises definingone of the levels of wear to be between 80% and 50% of a remaining wear,and defining another of the levels of wear to be between 20% and 10% ofthe remaining wear or between 20% and 15% of the remaining wear.
 25. Themethod according to claim 15, which further comprises: defining at leastone threshold value for the remaining operating time; checking whetheror not the remaining operating time falls below the at least one definedthreshold value; and generating an advice signal if the remainingoperating time falls below the at least one defined threshold value. 26.The method according to claim 25, which further comprises at least oneof displaying the advice signal on an optical or acoustic display deviceor forwarding the advice signal to a further computer system.
 27. Themethod according to claim 15, which further comprises carrying out thestep of predicting the remaining operating time of the sealing elementas at least one of a single value or an interval.
 28. A sealingassembly, comprising: a device for monitoring a sealing structureincluding at least one sealing element for sealing at least one negativeor positive pressure zone adjoining a surface moving in a direction ofmovement in a machine for producing or processing a fibrous web; atleast one wear sensor associated with said at least one sealing element;a signal transmission device for transmitting a signal from said atleast one wear sensor; and a computer system receiving the signal fromsaid signal transmission device, said computer system being configuredto carry out the following steps: providing a time z0 at which thesealing element became operational; providing a time z1 at which adefined first level of wear of the sealing element was reached;providing at least one further characteristic variable describing amachine speed, operating times of the machine, stoppage times of themachine, at least one of type or quantity of products being produced, ora contact pressure of the sealing element onto the moving surface; andpredicting a remaining operating time of the sealing element from thetimes z0 and z1 and the at least one further characteristic variable.29. The sealing assembly according to claim 28, wherein the computersystem predicts the remaining operating time of the sealing element froma time difference between z0 and z1 and the at least one furthercharacteristic variable.
 30. The sealing assembly according to claim 28,wherein said at least one wear sensor includes a plurality of wearsensors.
 31. The sealing assembly according to claim 28, wherein said atleast one wear sensor includes at least one of a wear sensor indicatinga level of wear of between 80% and 50% of a remaining wear or a wearsensor indicating a level of wear of between 20% and 10% of theremaining wear.
 32. The sealing assembly according to claim 28, whereinsaid at least one wear sensor includes at least one optical fiber, anelectrical conductor, a temperature sensor or a hose being filled with amedium, and said optical fiber, electrical conductor, temperature sensoror hose is destroyed with progressive wear of said sealing element.